The shooting deaths of a Hunterdon County couple and their adult son were likely a double murder and suicide, authorities said Sunday.

Hunterdon County Prosecutor Anthony Kearns III said 26-year-old Gabriel Wierzbicki apparently killed his 62-year-old father, Andrew Wierzbicki, and his 56-year-old mother, Wanda Wierzbicki, before killing himself. Their bodies were found late Saturday morning at the family's Kingwood Township home, but it's still not clear when -- or why -- the shootings occurred.

"It appears on the surface that a husband and his wife died at the hands of their son, who then killed himself," Kearns said Sunday. "Firearms were involved." Kearns said "a number of weapons" were recovered at the scene, but he declined to provide further details on the shootings, including what type of weapons were used or how many shots were fired, citing the ongoing investigation.

He said both state police and county authorities were involved in the probe, but a motive for
the shootings has not yet been determined.

Autopsies were scheduled to be performed Sunday on all three family members. The two murders were the first to occur in the rural municipality in more than 20 years. "Our sincere thoughts are with the family and this community," Kearns said. "It is a difficult task to investigate such a horrific incident such as this. We have some of the best state troopers and detectives working hard to determine what led up to this tragedy. I commend their teamwork."

State police had gone to the family's home after a 911 caller reported seeing a body there. Troopers soon found all three victims, and the home was quickly cordoned off while investigators combed the site for several hours.

Kearns said the shootings were an isolated incident that did not pose any "threat or danger" to the community.

Neighbors described the family as "quiet but troubled." Gabriel Wierzbicki had been in trouble with the law on several occasions in recent years, and he had recently returned home from college to look for a job.

Wanda Wierzbicki, a former receptionist for a local medical practice, was a self-published author. Her 2009 book, "Without Surrender," chronicled the life of her brother, Sgt. William Blahut, an Army veteran of the Iraq War who died of cancer the day before his unit returned from a yearlong deployment.

(Copyright 2012 by The Associated Press.  All Rights Reserved.)